Mat of ribbon shaped mineral fibers having a reflective coating



March 21, 1967 w. P. WARTHEN 3,310,455

MAT OF RIBBON SHAPED MINERAL FIBERS HAVING A REFLECTIVE COATING OriginalFiled Sept. 11. 1957 INVENTORZ WZLLJAM F X12 THEN.

.ATTYS.

United States Patent division of application Ser. No. 683,278, Sept. 11,1957,

now Patent No. 3,010,146. Divided and this application Dec. 24, 1964,Ser. No. 421,015

7 Claims. (Cl. 161-170) This is a division of my copending application,Serial Number 96,568, now Patent number 3,231,459 filed March 17, 1961,which is a division of my application, Serial Number 683,278 filed Sept.11, 1957, now Patent 3,010,146.

This invention relates to mineral fibers or filaments of ribbon-likeshape formed of heat-so-ftenable mineral materials and to a method andapparatus for producing same by attenuation.

Attempts have been made to fashion mineral materials into flat fibers orfilaments of noncircular cross-section but such endeavors have not beensuccessful by reason of the inherent characteristic of molten mineralmaterial such as glass in a plastic or flowable state to assume theconfiguration of circular cross section. This condition obtains eventhough the molten mineral material is discharged or extruded throughorifices of noncircular cross section, the surface tension and molecularinteradhesion being of sufficient magnitude to cause the material toimmediately form a substantially circular cylindrical body or stream. Byreason of this characteristic, fibers or filaments formed fromheat-softened mineral materials by attenuation have been ofsubstantially circular cross section.

Ribbon or film glass of a thickness of a few microns has been producedby methods involving the delivery of a tubular stream of softened glassbetween mechanically driven rolls which squeeze the tubular formation toa flat film, one method of this character being disclosed in the Slayterand Snow Patent 2,457,785 granted December 28, 1948. Another methodinvolves flowing or drawing glass in the form of a thin walled cylinderwhich is broken into small flakes. Attempts have been made to produce athin ribbon of glass through the use of drawing rolls but it has beenfound that the glass stream tends to neck in to a fraction of itsinitial width and there is a tendency for the formation of a bead orridge to be formed along the edges due to surface tension, and suchattempts have resulted in failure. As far as I am aware attempts toproduce fiat fibers or filaments by direct attenuation from a stream ofmolten mineral material have heretofore been unsuccessful.

The present invention embraces a method of successfully forming fibers,filaments or thin films of mineral material of noncircular cross-sectionby direct attenuation of a stream of the material.

An object of the invention embraces the provision of a method of formingflat fibers, continuous filaments or film by establishing differentialthermal conditions in different regions in a body of mineral materialand attenuating material from the body.

An object of the invention resides in a method involving feedingheat-softened material to a partially confined zone to establishdifferential thermal conditions in the material with consequentvariations in viscosity in different regions in the material andattenuating the material to form filaments, fibers or film ofnoncircular cross-section.

Another object of the invention is the provision of a method whereinmolten filament or film-forming material is delivered to a walled regionhaving an open area and 3,310,455 Patented Mar. 21, 1967 the materialsuspended in said region subjected to differential cooling enabling theattenuation of the material into a linear body of substantiallyrectangular crosssection.

Another object of the invention is the provision of an apparatus forflowing fiber or film forming material from a supply to a generallycubically shaped region having an open area in which region the materialis suspended and the material at the open area cooled at an increasedrate whereby the material may be drawn into a linear body of a widthgreater than its thickness.

Another object of the invention is the provision of a method andapparatus for producing flat fibers from heatsoftened mineral materialand coating one or more surfaces of the fibers with a suitable metal oralloy concomitantly with the attenuation operation whereby the metalcoating is fixedly bonded to the fibers.

A further object of the invention resides in a method of forming mineralmaterial into fiat fibers which may be twisted during attenuation toform a spirally shaped fiber.

Another object is the provision of a method and apparatus for thermallycontrolling a body of fiber or film- 'forming material to establishthermal differentials in different regions of the body of materialwhereby the same may be drawn or attenuated into flat fibers or film ofsubstantially uniform thickness.

Still a further object of the invention is the provision of an apparatusadaptable for attenuating a body of heatsoftened material into a fiatcontinuous filament or fiber by winding the attenuated film or fiberupon a collet moving at high speed whereby fiat fibers of extremefineness may be efficiently produced with inexpensive equipment.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements per se, and to economics of manufactureand numerous other features as will be apparent from a consideration ofthe specification and drawing of a form of the invention, which may bepreferred, in which:

FIGURE 1 is a semidiagrammatic view with certain parts shown in sectionillustrating a type of apparatus for forming flat fibers or film fromheat-softened mineral material;

FIGURE 2 is a front elevational view of the arrangement shown in FIGURE1;

FIGURE 3 is a view similar to FIGURE 1 illustrating a method of applyinga coating or layer of metal or other material to completely surround aflat filament or fiber;

FIGURE 4 is a fragmentary isometric view of a flat fiber illustrating acoating of metal on one major face thereof;

FIGURE 5 is an isometric view illustrating a fiat fiber completelycoated with metal or other material;

FIGURE 6 is. a fragmentary view showing a flat fiber oriented in aspiral or twisted formation, and

FIGURE 7 is a semidiagra-mmatic view illustrating the method of formingcomparatively thin film of heatsoftened material by attenuation.

The method and apparatus of the invention are especially adapted forproducing fiat or ribbon-like continuous filaments, fibers or film fromheat-softenable minerals, such as glass, slag, or fusible rock. However,it is to be understood that the principles involved in the formation offlat filaments, fibers or film may be utilized for the production oflinear bodies of other noncircular crosssectional configurations throughthe establishment of thermal differentials in various regions of a bodyor quantity of material from which the linear bodies are drawn orattenuated.

Referring to the drawings in detail, a form of apparatus is illustratedfor carrying out the method of the invention which includes areceptacle, tank or feeder containing a supply 12 of heat-softened glassor other fiber or filmforming mineral material. The receptacle 10 may bea forehearth connected with a melting furnace in which glass batch isreduced to a molten state or in the form of an independent feederreceptacle adapted to be heated by electrical energy in a conventionalmanner.

When a heated feeder is utilized, the fiber or filmforming material ispreferably delivered into the receptacle as preformed marbles or sphereswhich are reduced to molten or a fiowable state by heat applied to thefeeder.

The glass in the feeder or receptacle is delivered to a partiallyconfined zone configurated or shaped to set up thermal or temperaturedifferentials to modify the viscosity of the material in differentregions thereof whereby a linear body of noncircular cross-section maybe drawn from the material. Disposed beneath the floor 14 of thereceptacle 10 is a member or shield 16 which, in the embodimentillustrated is of three-sided configuration including a rear wall 18 andspaced side walls 20.

The walls or fins 18 and 20 define or establish a reservoir or chamber22 of generally cubical shape as the walls 18 and 20 are substantiallysquare. The walls are Welded as at 24 or otherwise securely joined tothe bottom wall or floor 14 of the receptacle 10 as shown in FIGURES 1and 2. An orifice or passage 26 is formed in the bottom wall 14 throughwhich glass 12 or other mineral material from the receptacle fiows intothe chamber or partially confined zone 22. The glass in the receptacleis maintained at a temperature rendering the glass quite viscousalthough fiowable.

In carrying on fiber or film-forming operations the operator, throughthe use of a suitable tool, diverts or deflects the heat-softened glassflowing through the orifice 26 into contact with the inner surfaces ofthe Walls 18 and 20 and the lower surface of bottom wall 14 of thereceptacle to wet the walls so that the fiowable glass will adhere tothe wall surfaces.

This action floods the chamber 22 with the glass to form a body orquantity 28 of glass in the chamber which, during attenuatingoperations, assumes a configuration of the general contour as indicatedin FIGURE 1.

The glass or material in the feeder or receptacle 10 is maintained at atemperature whereby the viscosity of the glass in the chamber 22 is suchthat the glass is suspended from the walls. In the embodimentillustrated in FIG- URES 1, 2, 3 and 7, the rear wall 18 and the sideWalls 20 are substantially square and hence define a reservoir, chamberor region 22 which is substantially cubical in shape, the fourth sideand bottom being open or unrestricted.

Through the provision of an open sided reservoir, the surface 30 of thebody of glass 28 in the reservoir, is exposed to direct contact with theambient air while the remaining surface regions of the body of glass 28are in contact with the central region of the bottom wall 14 of thereceptacle and the interior surfaces of the rear and side walls 18 and20 forming the shield. Direct contact of the surface region 30 of thebody of glass 28 with the air chills or reduces the temperature of theglass at the region 30 at a faster rate than the regions of the glass incontact with the walls 18 and 20.

Hence thermal differentials are set up in different regions of the bodyof glass 28 establishing varying viscosities therein whereby the glassmay be drawn or attenuated from the reservoir 22 into a linear body,filament, fiber or film of noncircular cross-section.

As illustrated in FIGURE 1, the glass or other fiber or film-formingmaterial 28 is drawn or attenuated from the region at the lower terminusof the rear wall 18 in forming a linear body, the rear wall 18 being ofplanar shape and the attenuated linear body or filament 32 of flat orrectangular cross-section as shown in FIGURE 4.

The fiber or filament 32 is attenuated by being wound around a collet 35mounted upon a rotating arbor 36, the collet being rotated at a desiredspeed by a motor (not shown) to secure a fiber or filament of desiredsize.

The principles involved in the method of successfully forming a linearbody, filament or fiber of noncircular cross-section through the use ofthe apparatus disclosed are as follows: The body of glass 28 is of aviscous constituency so that it is supported and suspended by adhesionto the walls of the shield 16. The exposed surface region 30 of the bodyof glass 28 is cooled and its temperature reduced by contact with theambient air at a faster rate than those regions of the body in contactwith the walls 18 and 20.

This cooling action substantially increases the viscosity of the glassat the surface region 30 and tends to retard the necking in of the glassbeing drawn from the terminus of the rear wall 18 of the shield as theglass at the surface region 30 converging at the region indicated at 38approaches a state of solidification. This condition providessubstantial resistance to flow of the glass and is sufiicient to preventthe natural or inherent tendency for glass to gravitate to a circularcross-section.

The glass in contact with the walls 18 and 20 is at higher temperaturesand hence lower viscosities and flows into convergence with the moreviscous glass at the region 38 from which the filament or body is drawnor attenuated. As shown in FIGURE 2, the glass is drawn from atransverse linear zone 38 provided by the terminus of the planar wall 18and as the glass leaves the wall 18 it is of rectangular cross-sectionand is solidified by further contact with air into a flat linear body orfilament 32. Several factors affect the cross-sectional configuration,the width and thickness of the attenuated body or filament. Theviscosity of the body of glass in the reservoir 22 should be high enoughto maintain a condition of constant flooding in the region defined bythe Walls 18 and 20, as the space between the side walls 20 must befilled with softened glass and the walls 18 and 20 wetted by the glassin order to secure a flat filament or fiber. It is believed that thetendency for the glass to Wet over the surface of the wall 18 includingthe terminus region thereof from which the filament is drawn is animportant factor in forming the flat filaments or fibers. The linearrate of attenuation in 'a large measure determines the Width andthickness of the attenuated body.

As an operating example, an apparatus is employed wherein the walls 18and 20 are each substantially /2" square and the passage or orifice 26in the floor of the receptacle 10 is approximately in diameter. Byattenuating the body, filament or fiber at the rate of upwards of tenthousand linear feet per minute, a flat ribbon-like continuous filamentor fiber of a thickness of two or more microns and of a widthapproximately eight to twelve times its thickness is formed.

By varying the operating factors above-mentioned, the thickness andwidth of the attenuated filament or fiber may be varied and controlled.The relative dimensions. of the rear and side walls of the shroud 16,and the spacing between the side walls, may be varied to modify thewidth and thickness of the flat filament.

Furthermore, while the configuration of the shield 16 illustrated isparticularly adapted to form flat, ribbon-like filaments or fibers themajor surfaces of which are in parallelism, it is to be understood thatthe shape of the walled shroud or shield 16 may be modified to produceattenuated linear bodies of other noncircular cross-sectionalconfigurations. Variations in cross-sectional configuration may beobtained by varying the thermal differential between the glass at theregion indicated at 30 in FIGURE 1 and that adjacent or in contact withthe inner surfaces of the walls 18 and 20 by directing a controlled airstream toward the exposed region 30 of the glass 28 in the zone 22.

The flat, ribbon-like fibers or filaments produced by the method andapparatus above described may be surface coated with other materials,such as metals, metal alloys or other glasses. FIGURE 1 illustrates anarrangement for applying a coating of metal to one face or surface of aflat filament 32. Disposed adjacent the filament 32 is 'a receptacle 40adapted to contain a supply of molten metal 42. The receptacle 40 isformed with a lip 44 which is positioned adjacent the path of movementof the fiat filament 32.

The molten metal 42 flows from the supply in the receptacle onto the lip44, the adjacent flat surface of the fiber 32 engaging the moten metalon the lip 44 whereby during linear movement of the filament, onesurface thereof is coated with the metal. The transfer of the moltenmetal onto the filament is effected by a wiping action enhanced by. theinherent characteristic of glass to acquire a coating on a nascentsurface.

Metals that have been found suitable for coating the filaments or fibersare aluminum, chromium, zinc, lead or the like. The winding collet 35 isspaced a distance suflicient form the region of application of thecoating to the filament so that the metal is completely set orsolidified before the coated filament is wound onto the collet. FIGURE 4illustrates a flat fiber 32 with a metal coating 33 thereon. The metalcoating is preferably applied to the filament at or just prior to thepoint of complete attenuation or solidification of the glass.

FIGURE 3 is [illustrative of an arrangement similar to FIGURE 1 forcompletely coating a flat filament or fiber with metal. In thisarrangement, the receptacle 40' contains molten metal 42' which flowsonto a lip 44 providing a quantity of the coating metal at 45. Thefilament 32 is pulled or drawn through the meniscous of metal 45 so thatboth major surfaces and the edge regions receive a coating 33' of themetal. In order to eflect a complete coating on the fiat filament 32,the filament is drawn away from the terminus of the wall 18' in anangular direction as shown in FIGURE 3, to completely immerse thefilament in the metal supported on the lip 44'. FIGURE 5 illustrates theflat fiber or filament 32 completely embedded in or surrounded by themetal coating 33'.

The coated or uncoated flat continuous filament may be twisted prior toits collection upon a winding collet. The twisting of the flat filamentor fiber may be accomplished by passing the filament through a rotatingguide (not shown) having a transversely elongated opening in the axialregion thereof to accommodate the flat filament.

By rotating the guide, the wall surfaces defining the elongated slot inthe guide engage and twist the filament to the configuration shown at32a in FIGURE 6. The amount of twist or spiral configuration imparted tothe fiber or filament 32a may be modified by varying the speed ofrotation of the twisting guide or varying the ratio of speed of rotationof the winding collet 35 to that of the twisting means.

The arrangement of receptacle and the chamber 22 provided by the wallsor fins 18 and 20 may be utilized to produce thin film glass ofsubstantial width in the manner shown in FIGURE 7. In forming filmglass, the glass of the body 28' contained in the reservoir or chamber22 is preferably drawn in a substantially horizontal or lateraldirection from the shield 16.

In forming film glass in the manner illustrated in FIG- URE 7, both thesurface regions of the body of glass 28' exposed to the ambient airthrough the open side and the open bottom region of the shield arechilled and the viscosity increased so that during attenuation of thefilm 48, the chilled regions are drawn into coextensive convergingrelation and by reason of the increased viscosity, the linear body orfilm does not neck in appreciably.

Thus, a glass film of a width only slightly less than the transversedimension between the walls 20 is formed,

the thickness and width of the film being determined in a large measureby the initial viscosity of the glass 28' in the chamber 22, the extentof temperature reduction or chilling of the exposed regions of the bodyof glass 28' and the rate of linear attenuation of the film. The filmmay be attenuated by pull rolls or other suitable means.

The attenuated film 48 may be coated with metal on one or both surfacesby feeding molten metal onto the film. The molten metal is preferablyapplied to the film before attenuation is complete in order to improvethe adhesion between the molten metal and the glass. 7 While a singlefilament or fiber attenuating unit is illustrated, associated with thereceptacle 10, it is to be understood that a substantial number of units16 may be secured to a glass feeder or bushing associated with aforehearth of a glass melting furnace whereby a substantial number offlat filaments or fibers may be formed concomitantly.

The flat filaments or fibers are adaptable for many and varied uses. Theuncoated fibers may be processed into filter mats to obtain improvedfiltering efliciency. For example, the flat filaments or fibers may beoriented in a general pattern with their major surfaces facing in thesame direction and in overlapping relation. This orientation causes agreater turbulence of the air or other gas passing through the filter indirections generally normal to the major surface of the filaments andenhances the removal of foreign matter. Flat filaments may be used forpolarization or light channeling purposes.

The metal coated flat filaments or fibers are adaptable for many uses.For example, coated fibers may be used for decorative purposes. Whencoated on one side with metal, they are highly reflective and becomeminiature mirrors. The spiral fibers, both coated and uncoated areuseful for decorative purposes. Metal coated fibers may be processedinto mats having high insulating efficiency. By orienting the metalcoated surfaces of the fibers whereby they face generally in onedirection in a mat, the coated surfaces, being heat reflective, providereflective insulating properties in addition to the conventionalinsulating characteristics of a fibrous mat.

The method of the invention may be employed in forming laminated unitssuitable for electrostatic condensers. For example, two flat filamentsmay be concomitantly formed, one of the filaments coated with metal onone face and the two fibers brought into engaging relation with themetal disposed between the fibers providing a glass and metal laminate.Metal coated filaments may be employed in producing electrostaticfilters, high frequency signal reflection, or electromagnetic energyreflection and for current conducting purposes.

The film glass formed by the method exemplified in FIGURE 7 may becoated with metals or other glass by feeding the coating materials tothe softened glass within the region defined by the walls 18 and 20 orapplied to the film at or in advance of the zone of completeattenuation.

Curly filaments may be produced by feeding a coating glass having adifferent coefficient of expansion onto the filaments in softenedcondition.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than is herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

I claim:

1. An article of manufacture comprising an attenuated filament ofmineral material of substantially rectangular cross section, and acoating of reflective material bonded 3. An article of manufacturecomprising an attenuated filament of glass of rectangular cross sectionof a Width of approximately eight to twelve times its thickness, and acoating of reflective material surrounding and bonded to the filament.

4. A fibrous mat comprising a mass of metal coated mineral fiberswherein the fibers are of rectangular cross section.

5. A fibrous mat comprising a mass of mineral fibers wherein the fibersare of rectangular cross section, and a heat reflective coating on thefibers.

6. An article of manufacture comprising a glass filament of rectangularcross section, and a coating of material on said glass filament having acoefficient of expan sion diiferent from that of the glass of thefilament.

7. An article of manufacture comprising a glass filament of rectangularcross section, and a coating of glass on said glass filament, the glassof the coating having a coeflicient of expansion different from that ofthe glass of the filament.

References Cited by the Examiner UNITED STATES PATENTS 2,509,845 5/1950Slayter 65193 2,578,986 12/1951 Schoonenberg 65191 2,616,165 11/ 1952Brennan.

2,687,673 8/1954 Boone.

2,714,569 8/1955 Prindle et al. 161-175 2,772,518 12/ 1956 Whitehurst etal. 653 2,909,151 10/1959 Cahn 117126 2,938,821 5/1960 Nack 6533,076,324 2/1963 Morgan 6511 EARL M. BERGERT, Primary Examiner.

ALEXANDER WYMAN, Examiner.

R. A. FLORES, Assistant Examiner.

3. AN ARTICLE OF MANUFACTURE COMPRISING AN ATTENUATED FILAMENT OF GLASSOF RECTANGULAR CROSS SECTION OF A WIDTH OF APPROXIMATELY EIGHT TO TWELVETIMES ITS THICKNESS, AND A COATING OF REFLECTIE MATERIAL SURROUNDING ANDBONDED TO THE FILAMENT.